Comment 5 for bug 1453738

OK, so you actually have one unencrypted swap partition on an LVM LV:
/dev/mapper/ubuntu--vg-swap_1: UUID="bfa46f63-6942-4d4b-b1ce-b7c3df4f3818" TYPE="swap"

and your /etc/fstab configures just that. But your crypttab configures an encrypted swap device which isn't in fstab:

cryptswap1 /dev/dm-1 /dev/urandom swap,cipher=aes-cbc-essiv:sha256

That's presumably what's causing the password prompt. Let's check which LV dm-1 actually is, can you please get me the output of "ls -lR /dev/mapper"? I am 95% sure it's /dev/mapper/ubuntu--vg-swap_1 and thus this swap partition is used as *both* an encrypted and unencrypted one, and the former fails because of the latter:

mei 11 07:32:36 Denny-HP systemd-cryptsetup[748]: Set cipher aes, mode cbc-essiv:sha256, key size 256 bits for device /dev/dm-1.
mei 11 07:32:36 Denny-HP systemd-cryptsetup[748]: Failed to activate with key file '/dev/urandom': Device or resource busy

So this looks like an LVM variant of bug 953875, not of bug 1447282; this looks independent of GPT.